Is there a function that calculates the power of a repeated-measure ANOVA design, e.g., 2 groups, 4 within-subject factors, an average 0.40 correlation between the 4 within factors, etc. I don't think I can use power.anova.test() because it does not consider corr=0.40. I am hoping that someone has already implemented the method by Muller & Barton (1989, JASA 84: 549-555) on how to approximate statistical power for a univariate test in repeated-measures ANOVAs when the sphericity assumption is not met. If not, perhaps the MANOVA approach by O'Brien & Kaiser (1985, Psych Bull: 97, 316-33). library(pwr) does not seem to support either. Many thanks in advance, Yuelin Li. ==================================================================== Please note that this e-mail and any files transmitted with it may be privileged, confidential, and protected from disclosure under applicable law. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any reading, dissemination, distribution, copying, or other use of this communication or any of its attachments is strictly prohibited. If you have received this communication in error, please notify the sender immediately by replying to this message and deleting this message, any attachments, and all copies and backups from your computer.
Thomas Lumley
2011-Mar-10 19:25 UTC
[R] power for repeated-measures ANOVA lacking sphericity
On Fri, Mar 11, 2011 at 6:08 AM, Yuelin Li <liy12 at mskcc.org> wrote:> Is there a function that calculates the power of a > repeated-measure ANOVA design, e.g., 2 groups, 4 > within-subject factors, an average 0.40 correlation between > the 4 within factors, etc. > > I don't think I can use power.anova.test() because it does > not consider corr=0.40. >The easiest approach is likely to be simulation: simulate data from the design and compute the p-value, repeat a few thousand times. -thomas -- Thomas Lumley Professor of Biostatistics University of Auckland
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